1. Field of the Invention
The present invention concerns a sound output tube for direct connection to an emission port of an earpiece (earphone) of a hearing device that is produced as an injection molded part. In this context, a “hearing device” encompasses an in-the-ear device such as a hearing system, a headset, headphones and the like.
2. Description of the Prior Art
Hearing systems are wearable hearing devices that serve to assist hearing impaired persons. In order to meet the numerous individual requirements, different structural shapes of hearing systems such as behind the ear (BtE) hearing systems and in the ear (ItE) hearing systems as well as concha hearing systems or completely in canal (CIC) hearing systems are provided, for example. These hearing systems listed as examples are worn on the outer ear or in the auditory canal. Moreover, bone conduction hearing aids, implantable, and vibrotactile hearing aids are also commercially available. The stimulation of the damaged ear ensues either mechanically or electrically.
In principle hearing systems have as basic components an input transducer, an amplifier and an output transducer. The input transducer is normally a sound receiver (for example a microphone) and/or an electromagnetic receiver (for example an induction coil). The output transducer is usually realized as an electro-acoustic transducer (for example a miniature speaker) or as an electromechanical transducer (for example a bone conduction earpiece). The amplifier is typically integrated into a signal processing unit. This basic design is shown in FIG. 1 in the example of a behind the ear hearing system. One or more microphones 2 for acquisition of the sound from the environment are installed in a hearing device housing 1 to be worn behind the ear. A signal processing unit 3 that is likewise integrated into the hearing device housing 1 processes the microphone signals and amplifies them. The output signal of the signal processing unit 3 is transferred to a speaker or earpiece 4 that outputs an acoustic signal. The sound is possibly transferred to the eardrum of the system wearer via a sound tube that is fixed in the auditory canal with an otoplastic. The power supply of the hearing system and in particular that of the signal processing unit 3 ensues via a battery 5 likewise integrated into the hearing device housing 1.
The earpiece 4 is connected with its output to a connection piece 6. This simultaneously serves as a mechanical plug connection or, respectively, fastening possibility for a support hook 7 as well as for transfer of the amplified sound from the earpiece 4 into a sound channel 8 of the support hook 7. From the support hook 7 the sound is typically directed to the auditory canal via a sound tube (not shown).
Given such a design of a BtE hearing system the danger exists that the earpiece transfers vibrations to the support hook or, respectively, the hearing device housing. The acoustic properties of the hearing system thereby change and in particular unintentional feedbacks arise. This means that the transfer function of the hearing system exhibits distinct spikes (peaks).
A solution to this problem is to design the connection piece from a softer material. Alternatively, a short sound emission tube that consists of a soft material is also inserted between the earpiece and the connection piece. However, this leads to the further problem that the earpiece is no longer held firmly enough in the hearing device housing. Given vibrations it can consequently strike the hearing device housing, whereby the acoustic stability is in turn reduced. Conversely, shocks that act on the hearing system from the outside can also be transferred to a less firmly seated earpiece. The risk exists that the earpiece is damaged or destroyed. The stability of a hearing system is checked in drop tests with which it can be simulated how robustly the hearing system responds upon being dropped.
Drop tests and earpiece vibrations require a damped mounting of the earpiece in the hearing device housing. A corresponding installation space therefore must be provided in the hearing device housing so that the earpiece can execute movements in a defined frame. Multiple corresponding adhesives or reinforced microphone hangings are utilized in order to achieve a damped mounting in this space. Moreover, it is also known to embed the earpiece in a polyurethane mold or to affix the hearing device housing with a soft silicone glue.
A soft sound emission tube and soft hangings of the earpiece lead to better acoustic properties of the hearing system or of the hearing device. However, this also requires a larger installation space for the earpiece since this must in particular be able to move correspondingly, in particular in drop tests. A compromise is thus sought that allows an optimally small installation space but in which the vibrations of the earpiece or of the hearing device housing are simultaneously sufficiently absorbed. Tradeoffs thus must be made between acoustic stability and mechanical design.
A hook for a hearing system is known from WO 2006/125434 A1. The hearing system hook has damping means in order to damp its mechanical vibrations. In particular a multipart hook is proposed whose middle part consists of a damping material. The hook can as a whole be produced in a multi-component injection molding method. Silicone is suitable as a damping material, for example.
A hearing system in which at least two of the parts to be assembled thereon are produced from different materials in two-component or multi-component injection techniques are known from the printed document EP 1 492 383 A1. For example, a seal is injected as well in a border region of a shell part in a two-part or multi-part shell of a hearing system.